Delay locked loop semiconductor apparatus that models a delay of an internal clock path

ABSTRACT

A delay locked loop semiconductor apparatus that models a delay of an internal clock path is presented. The semiconductor apparatus includes: a DLL and a detection code output block. The DLL includes a delay model unit in which a delay value of an internal clock path is modeled and is configured to output a DLL clock signal of which the phase is controlled by reflecting the delay value of the internal clock path into an applied input clock signal. The detection code output block is configured to output a phase difference detection code having a code value corresponding to a phase difference between a first phase correction clock signal generated by reflecting a model delay value of the delay model unit into the DLL clock signal and a second phase correction clock signal generated by reflecting an actual delay value of the internal clock path into the DLL clock signal.

CROSS-REFERENCES TO RELATED APPLICATION

The present application claims priority under 35 U.S.C. §119(a) toKorean application No. 10-2010-0016574, filed on Feb. 24, 2010, in theKorean Intellectual Property Office, which is incorporated herein byreference in its entirety as set forth in full.

BACKGROUND

1. Technical Field

The present invention relates to a semiconductor apparatus, and moreparticularly, to a technology which corrects a difference between amodel delay value of a delay locked loop (DLL) and an is actual delayvalue.

2. Related Art

A semiconductor apparatus operates in synchronization with a referenceperiodic pulse signal, such as a clock signal, in order to improve anoperation speed and to effectively perform an internal operation.Therefore, most semiconductor apparatuses operate using a clock signalsupplied from outside or an internal clock signal generated depending onthe particular necessity and/or configuration.

Meanwhile, an input clock signal applied to a semiconductor apparatus isdelayed internally in the semiconductor apparatus. Therefore, when datais outputted by using the delayed clock signal, the outputted data maynot be synchronized with the input clock signal. Accordingly, thesemiconductor apparatus compensates for a phase difference between theinput clock signal and the internal clock signal using a delayed lockloop (DLL), a phase locked loop (PLL) and so on.

FIG. 1 is a configuration diagram of a conventional semiconductorapparatus.

Referring to FIG. 1, the conventional semiconductor apparatus mayinclude a DLL 2 which includes an internal clock path composed of aplurality of repeaters 3 and 5, a transfer line 4, and an output drivingunit 6.

The DLL 2 is configured to output a DLL clock signal DLL_CLK of whichthe phase is controlled by reflecting a delay value of the internalclock path into an applied input clock signal EXT_CLK. Since theinternal clock path has a delay value of ‘tDO’ the DLL 2 advances thephase of the input clock signal EXT_CLK by a delay value of ‘−tDO’ togenerate the DLL clock signal DLL_CLK. Therefore, an output clock signalSTB_CLK which is finally outputted through the internal clock path hasthe same phase as the input clock signal EXT_CLK.

Meanwhile, the DLL 2 may include a delay model unit (not shown) in whichthe delay value of the internal clock path is modeled. The delay modelunit is designed in such a manner as to have substantially the samedelay value as that of the internal clock path in the ideal case. In thedelay model unit in which the components of the internal clock path aremodeled, however, the positions of the components are different fromthose of actual components. Between the model delay value and the delayvalue of each component, a difference may occur. In particular, thedifference may further increase due to changes in process and voltage.Such a difference between the delay values may cause a reduction intiming margin of an internal circuit which operates using the DLL clocksignal DLL_CLK. Therefore, there is demand for a technology capable ofsolving such a problem.

SUMMARY

In one embodiment of the present invention, a semiconductor apparatusincludes: a DLL including a delay model unit in which a delay value ofan internal clock path is modeled and configured to output a DLL clocksignal of which the phase is controlled by reflecting the delay value ofthe internal clock path into an applied input clock signal; and adetection code output block configured to output a phase differencedetection code having a code value corresponding to a phase differencebetween a first phase correction clock signal generated by reflecting amodel delay value of the delay model unit into the DLL clock signal anda second phase correction clock signal generated by reflecting an actualdelay value of the internal clock path into the DLL clock signal.

In another embodiment of the present invention, a semiconductorapparatus includes: a DLL including a delay model unit, in which a delayvalue of an internal clock path is modeled and of which a model delayvalue is controlled depending on a voltage level of a bias controlvoltage, and configured to output a DLL clock signal of which the phaseis controlled by reflecting the delay value of the internal clock pathinto an applied input clock signal; and a control voltage output blockconfigured to output the bias control voltage having a voltage levelcorresponding to a phase difference between a first phase correctionclock signal generated by reflecting the model delay value of the delaymodel unit into the DLL clock signal and a second phase correction clocksignal generated by reflecting an actual delay value of the internalclock path into the DLL clock signal.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, aspects, and embodiments are described in is conjunction withthe attached drawings, in which:

FIG. 1 is a configuration diagram of a conventional semiconductorapparatus;

FIG. 2 is a configuration diagram of a semiconductor apparatus accordingto first embodiment;

FIG. 3 is a detailed configuration diagram of a code generation unit;

FIG. 4 is a configuration diagram of a semiconductor apparatus accordingto a second embodiment;

FIG. 5 is a detailed configuration diagram of a voltage generation unit;and

FIG. 6 is a timing diagram showing the internal operation of thesemiconductor apparatus according to the second embodiment.

DETAILED DESCRIPTION

Hereinafter, a semiconductor apparatus according to the presentinvention will be described below with reference to the accompanyingdrawings through preferred embodiments.

FIG. 2 is a configuration diagram of a semiconductor apparatus accordingto first embodiment.

The semiconductor apparatus according to this embodiment includes only asimple configuration for clearly explaining the technical spirit to beproposed.

Referring to FIG. 2, the semiconductor apparatus includes a DLL 20, adetection code output block 30, an internal clock path is formed from aplurality of repeaters 41 and 43, a transfer line 42, and a clock outputdriving unit 44.

The detailed configuration and main operation of the semiconductorapparatus configured in such a manner will be described as follows.

The DLL 20 includes a delay model unit 25 in which a delay value of theinternal clock path is modeled, and is configured to output a DLL clocksignal DLL_CLK in which the phase is controlled by substantiallymatching that of the delay value of the internal clock path into anapplied input clock signal EXT_CLK.

That is, the DLL 20 includes a clock input buffer 21, a variable delayunit 23, a delay model unit 25, a phase comparison unit 22, and a delaycontrol unit 24. The clock input buffer 21 is configured to output aninternal clock signal INT_CLK by buffering the input clock signalEXT_CLK. The variable delay unit 23 is configured to delay the internalclock signal INT_CLK outputted from the clock input buffer 21 to outputa DLL clock signal DLL_CLK. The delay model unit 25 is configured tooutput a first phase correction clock signal FEED_CLK obtained bydelaying the DLL clock signal DLL_CLK by a model delay value. The phasecomparison unit 22 is configured to compare the phases of the internalclock signal INT_CLK and the first phase correction clock signalFEED_CLK. The delay control unit 24 is configured to control the delayvalue of the variable delay unit 23 as a function of the comparisonresult of the phase comparison unit 22. For reference, the DLL 20performs a locking operation when is the phase of the internal clocksignal INT_CLK is identical to that of the first phase correction clocksignal FEED_CLK. The delay value of the variable delay unit 23 is fixedwhen the locking operation is performed. The delay control unit 4 may beimplemented as a shift register.

When it is assumed that the internal clock path has a delay value of‘tBUF+tDO’, the delay model unit 25 is designed in such a manner as toideally have a delay value of ‘tBUF+tDO’. The DLL 20 advances the phaseof the input clock signal EXT_CLK by a delay value of ‘−tDO−tBUF’ togenerate a DLL clock signal DLL_CLK. Therefore, a second phasecorrection clock signal STB_CLK which is finally outputted through theinternal clock path has substantially the same phase as that of theinput clock signal EXT_CLK.

Meanwhile, a difference may still occur between the model delay value ofthe delay model unit 25 and an actual delay value of the internal clockpath, because of a difference between positions at which circuits aredisposed and changes in process and voltage which are different from theideal case.

The detection code output block 30 outputs a phase difference detectioncode SCODE<0:15> having a code value corresponding to a phase differencebetween the first phase correction clock signal FEED_CLK generated bysubstantially matching the model delay value of the delay model unit 25into the DLL clock signal DLL_CLK and the second phase correction clocksignal STB_CLK generated by substantially matching the actual delayvalue of the internal clock path into the DLL clock signal DLL_CLK.

The detection code output block 30 includes a code generation unit 31and an output driving unit 32. The code generation unit 31 is configuredto compare the phases of the first and second phase correction clocksignals FEED_CLK and STB_CLK in a test mode and configured tosubsequently generate a phase difference detection code SCODE<0:15>corresponding to the comparison result. The output driving unit 32 isconfigured to output the phase difference detection code SCODE<0:15> tothe outside through a pad PAD. Therefore, the phase difference detectioncode SCODE<0:15> outputted through the pad PAD may be analyzed by testequipment to check a difference between the model delay value and theactual delay value.

FIG. 3 is a detailed configuration diagram of the code generation unit.

Referring to FIG. 3, the code generation unit 31 includes a phasecomparator 310, an enable signal generator 320, and a shift register330. The phase comparator 310 is configured to compare the phases of thefirst and second phase correction clock signals FEED_CLK and STB_CLK tooutput a phase detection signal DET. The enable signal generator 320 isconfigured to generate an enable signal ENABLE which is activated for apredetermined time, in response to a test signal TESTMODE. The shiftregister 330 is configured to shift an internal code value in responseto the phase detection signal DET during the activation interval of theenable signal ENABLE.

The enable signal generator 320 includes a four-bit counter 321, a firstcontrol pulse generation unit 322, a second control pulse generationunit 323, pull-up and pull-down driving units MP1 and MN1, a latch unitINV1 and INV2 and an inverter INV3. The enable signal ENABLE is a signalwhich is activated while the four-bit counter 321 is counted for oneperiod, that is, counted 16 times in response to an internal clocksignal I_CLK. Therefore, the shift register 330 operates by receiving aclock signal corresponding to the internal clock signal I_CLK during theactivation interval of the enable signal ENABLE.

The phase comparator 310 may be configured in various manners. Forexample, the phase comparator 310 may be designed to output a high-levelphase detection signal DET when the phase of the first phase correctionclock signal FEED_CLK leads that of the second phase correction clocksignal STB_CLK and alternately configured to output a low-level phasedetection signal DET in the opposite case. Furthermore, the phasecomparator 310 may be designed to compare the phases of the first andsecond phase correction clock signals FEED_CLK and STB_CLK and output aphase detection signal DET having a pulse width corresponding to thephase difference therebetween. Furthermore, the phase comparator 310 maybe designed in such a manner as to compare the phases of the first andsecond phase correction clock signals FEED_CLK and STB_CLK and output aphase detection signal DET having a voltage level corresponding to thephase difference therebetween.

The shift register 330 right-shifts or left-shifts an internal codevalue in response to the phase detection signal DET and outputs a phasedifference detection code SCODE<0:15> corresponding to the internal codevalue.

FIG. 4 is a configuration diagram of a semiconductor apparatus accordingto a second embodiment.

Referring to FIG. 4, the semiconductor apparatus includes a DLL 20A, acontrol voltage output block 50, in which a plurality of repeaters 41and 43, a transfer line 42A, and a clock output driving unit 44A form aninternal clock path.

The detailed configuration and main operation of the semiconductorapparatus configured in such a manner will be described as follows.

The DLL 20A includes a delay model unit 25A in which a model delay valueis controlled as a function of the voltage level of a bias controlvoltage V_BIAS, and is configured to output a DLL clock signal CLL_CLKin which the phase is controlled by substantially matching a delay valueof the internal clock path into an applied input clock signal EXT_CLK.For reference, the delay model unit 25A has a modeled delay value of theinternal clock path.

That is, the DLL 20A includes a clock input buffer 21A, a variable delayunit 23A, a delay model unit 25A, a phase comparison unit 22A, and adelay control unit 24A. The clock input buffer 21A is configured tobuffer an input clock signal EXT_CLK. The variable delay unit 23A isconfigured to delay an internal clock signal INT_CLK outputted from theinput clock buffer 21A to output a DLL clock signal DLL_CLK. The delaymodel unit 25A is configured to output a first phase correction clocksignal FEED_CLK obtained by delaying the DLL clock signal DLL_CLK by amodel delay value. The phase comparison unit 22A is configured tocompare the phases of the internal clock signal INT_CLK and the firstphase correction clock signal FEED_CLK. The delay control unit 24A isconfigured to control a delay value of the variable delay unit 23A as afunction of the comparison result of the phase comparison unit 22A.

When it is assumed that the internal clock path has a delay value of‘tBUF+tDO’, the delay model unit 25A is designed to have a delay valueof ‘tBUF+tDO’ in the ideal situation. The DLL 20A advances the phase ofthe input clock signal EXT_CLK by a delay value of ‘−tDO−tBUF’ togenerate the DLL clock signal DLL_CLK. Therefore, a second phasecorrection clock signal STB_CLK which is finally outputted through theinternal clock path has the same phase as that of the input clock signalEXT_CLK.

Meanwhile, a difference may occur between the model delay value of thedelay model unit 25A and an actual delay value of the internal clockpath, because of a difference between positions at which circuits aredisposed and changes in process and voltage, different from an idealcase.

The control voltage output block 50 is configured to output a biascontrol voltage V_BIAS having a voltage level corresponding to a isphase difference between the first phase correction clock signalFEED_CLK generated by substantially matching the model delay value ofthe delay model unit 25A into the DLL clock signal DLL_CLK and thesecond phase correction clock signal STB_CLK generated by substantiallymatching the actual delay value of the internal clock path into the DLLclock signal DLL_CLK.

The control voltage output block 50 includes a code generation unit 31Aand a voltage generation unit 33. The code generation unit 31A isconfigured to compare the phases of the first and second phasecorrection clock signals FEED_CLK and STB_CLK and subsequently togenerate a phase difference detection code SCODE<0:15> having a codevalue corresponding to the comparison result. The voltage generationunit 33 is configured to generate a bias control voltage V_BIAS having avoltage level corresponding to the phase difference detection codSCODE<0:15>. The code generation unit 31A may be configured in the samemanner as the code generation unit 31 of FIG. 3. However, the codegeneration unit 31 of FIG. 3 is operated through control of the testsignal TESTMODE, and the code generation unit 31A is operated throughcontrol of a code enable signal CODE_EN.

When the phase of the first phase correction clock signal FEED_CLK leadsthe phase of the second phase correction clock signal STB_CLK, thevoltage level of the bias control voltage V_BIAS decreases incorrespondence to the phase difference. Since the voltage level of thebias control voltage V_BIAS decreases, the model is delay value of thedelay model unit 25A increases. Therefore, the model delay value iscontrolled to substantially match the same value as that of the actualdelay value.

The control voltage output block 50 according to this embodiment mayfurther include a code storage unit 34 and a selection unit 35. The codestorage unit 34 is configured to store the phase difference detectioncode SCODE<0:15>. The selection unit is configured to transfer a codeoutputted from the code generation unit 31A to the voltage generationunit 33 in a test mode and to transfer a code stored in the code storageunit 34 to the voltage generation unit 33 in a normal mode. Forreference, the code storage unit 34 is implemented as a fuse set.

Since the output driving unit 32A outputs the phase difference detectioncode SCODE<0:15> to the outside through a pad PAD, the phase differencedetection code SCODE<0:15> may be analyzed by a test equipment to checka difference between the model delay value and the actual delay value.Therefore, after an optimal phase difference detection code SCODE<0:15>is checked, the corresponding phase difference detection SCODE<0:15> isprogrammed into the code storage unit 34. Then, after a power-upoperation, the model delay value of the delay model unit 25A issubstantially corrected through the bias control voltage V_BIASgenerated by the phase difference detection code SCODE<0:15> stored inthe code storage unit 34. At this time, a first operation mode and asecond operation mode are determined by a mode selection signalMODE_SEL. In the first operation mode, the bias control voltage V_BIASis generated by the phase difference detection code SCODE<0:15>outputted from the code generation unit 31A in real time. In the secondoperation mode, the bias control voltage V_BIAS is generated by thephase difference detection code SCODE<0:15> stored in the code storageunit 34. However, without the code storage unit 34 and the selection 35,the bias control voltage V_BIAS corresponding to the phase differencedetection code SCODE<0:15> may be generated in real time.

For reference, the semiconductor apparatus may further include a codeencoder and a code decoder, in order to reduce the number of transferlines for transferring the phase difference detection code SCODE<0:15>.

FIG. 5 is a detailed configuration diagram of one embodiment of thevoltage generation unit.

Referring to FIG. 5, the voltage generation unit 33 includes a pluralityof voltage drop elements R1, . . . , RN−1, RN, R_REF, a plurality ofswitches SW_1 through SW_REF, a comparator 510, and a PMOS transistorMP1. The plurality of voltage drop elements R1 through R_REF areconnected between a power supply voltage terminal VDD and a groundvoltage terminal VSS. The plurality of switches SW_1 through SW_REF areconfigured to selectively output voltages divided by the respectivevoltage drop elements in response to the phase difference detection codeSCODE<0:15>. The comparator 510 is configured to compare the voltagedivided by the reference voltage drop element R_REF among the pluralityof voltage drop elements R1 through R_REF with a reference voltage VREFand output a control voltage corresponding to the comparison result. ThePMOS transistor MP1 is configured to supply a driving voltage to theplurality of voltage drop elements R1 through R_REF in response to theoutputted control voltage.

FIG. 6 is a timing diagram showing the internal operation of thesemiconductor apparatus according to the second embodiment.

Referring to the timing diagram of FIG. 6 and FIGS. 4 and 5, theoperation of the semiconductor apparatus according to the secondembodiment will be described as follows.

The code enable signal CODE_EN is a signal which is activated to a highlevel while the operation is performed.

In this embodiment, the DLL clock signal DLL_CLK is used as an internalclock signal I_CLK for controlling the code generation unit.

Since the phase of the first phase correction clock signal FEED_CLKleads the phase of the second phase correction clock signal STB_CLK inthe timing diagram, the phase detection signal DET transits to a highlevel.

While the enable signal ENABLE is activated to a high level, the shiftregister of the code generation unit right-shifts an internal code valueto output the phase difference detection code SCODE<0:15>.

The voltage level of the bias control voltage V_BIAS is is decreased bythe phase difference detection code SCODE<0:15> such that the mode delayvalue increases. Therefore, the phase of the first phase correctionclock signal FEED_CLK is finally corrected to substantially match thatof the second phase correction clock signal STB_CLK.

For reference, an encoding code EN_CODE<3:1> is a code generated byencoding the phase difference detection code SCODE<0:15>.

While certain embodiments have been described above, it will beunderstood to those skilled in the art that the embodiments describedare by way of example only. Accordingly, the semiconductor apparatusdescribed herein should not be limited based on the describedembodiments. Rather, the semiconductor apparatus described herein shouldonly be limited in light of the claims that follow when taken inconjunction with the above description and accompanying drawings.

1. A semiconductor apparatus comprising: a delay locked loop (DLL)comprising a delay model unit in which a delay value of an internalclock path is modeled and the DLL is configured to output a DLL clocksignal in which a phase of the DLL clock signal is substantiallycontrolled by the modeled delay value into an applied input clocksignal; and a detection code output block configured to output a phasedifference detection code corresponding to a phase difference between afirst phase correction clock signal generated by substantially matchingthe DLL clock signal with the modeled delay value and a second phasecorrection clock signal generated by substantially matching the DLLclock signal with an actual delay value of the internal clock path. 2.The semiconductor apparatus according to claim 1, wherein the detectioncode output block comprises: a code generation unit configured tocompare phases of the first and second phase correction clock signalsand configured to generate the phase difference detection codecorresponding to the comparison of the phases of the first and secondphase correction clock signals; and an output driving unit configured tooutput the phase difference detection code to the outside through a pad.3. The semiconductor apparatus according to claim 2, wherein the codegeneration unit comprises: a phase comparator configured to compare thephases of the first and second phase correction clock signals andconfigured to output a phase detection signal having a pulse width thatsubstantially corresponds to the phase difference of the first andsecond phase correction clock signals; an enable signal generatorconfigured to generate an enable signal which is activated for apredetermined time; and a shift register configured to shift an internalcode value in response to the phase detection signal when the enablesignal is activated.
 4. The semiconductor apparatus according to claim2, wherein the code generation unit comprises: a phase comparatorconfigured to compare the phases of the first and second phasecorrection clock signals and configured to output a phase detectionsignal having a voltage level that substantially corresponds to thephase difference of the first and second phase correction clock signals;an enable signal generator configured to generate an enable signal whichis activated for a predetermined time; and a shift register configuredto shift an internal code value to substantially correspond to a voltagelevel of the phase detection signal during the activation interval ofthe enable signal.
 5. The semiconductor apparatus according to claim 4,wherein the enable signal generator comprises a plural-bit countercontrolled by a test signal, and the enable signal generator isconfigured to activate the enable signal when the plural-bit counter iscounted for one period.
 6. The semiconductor apparatus according toclaim 1, wherein the second phase correction clock signal is delayed inaccordance to a plurality of elements in the internal clock path.
 7. Thesemiconductor apparatus according to claim 6, wherein the plurality ofelements in the internal clock path comprise a repeater, a transferline, and a clock output driving unit.